Practice question

Earliest tracheophytes like Rhynia gwynne-vaughanii and Cooksonia pertoni exhibited extremely simple sporophyte architecture reflecting transitional morphology. They possessed naked, dichotomously branched photosynthetic axes with thin cuticle, stomata, terminal sporangia and rhizoids for anchorage, but lacked true roots for absorption and leaves for expanded photosynthetic surface. Vascular strand was simple haplostelic protostele of annular tracheids. Roots with root caps and megaphyllous or microphyllous leaves evolved later via modification of branch systems through overtopping, planation, webbing and enation processes. This structural framework illustrates phylogenetic relationships and adaptive significance highlighted in competitive examinations focusing on comparative plant morphology and systematics.